On Wed, 2016-02-17 at 04:02 +0100, Mike Galbraith wrote: [...] > @stable: Kernels that predate SCHED_DEADLINE can use this simple (and tested) > check in lieu of backport of the full 18 patch mainline treatment. > > Signed-off-by: Mike Galbraith <umgwanakikb...@gmail.com> > --- > kernel/sched/fair.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -4008,6 +4008,7 @@ int can_migrate_task(struct task_struct > * 2) cannot be migrated to this CPU due to cpus_allowed, or > * 3) running (obviously), or > * 4) are cache-hot on their current CPU. > + * 5) p->pi_lock is held. > */ > if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) > return 0; > @@ -4049,6 +4050,14 @@ int can_migrate_task(struct task_struct > } > > /* > + * rt -> fair class change may be in progress. If we sneak in should > + * double_lock_balance() release rq->lock, and move the task, we will > + * cause switched_to_fair() to meet a passed but no longer valid rq. > + */ > + if (raw_spin_is_locked(&p->pi_lock)) > + return 0; > + > + /* > * Aggressive migration if: > * 1) task is cache cold, or > * 2) too many balance attempts have failed.
Queued up for 3.2, thanks. Ben. -- Ben Hutchings Any smoothly functioning technology is indistinguishable from a rigged demo.
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